1. Field of the Invention
The present invention relates to an electronic pen system that displays images on a touch surface of a touch panel corresponding to touch operations performed by an electronic pen and a finger to the touch surface.
2. Description of Related Art
An electronic pen system is conventionally known in which electronic pens and a touch panel are combined. In a capacitance type touch panel, a user can perform a touch operation by his/her fingertip as well as by an electronic pen (see Related Art 3, Related Art 4 and Related Art 5).
This kind of electronic pen system has been widely accepted and its use is widespread in the field of a personal computer or a portable information terminal. Further, a technology is known in which a touch panel is combined with a large-screen displaying device so as to be used as an interactive whiteboard for a presentation or a lecture directed at a large audience (see Related Art 1).
In use of this large-sized electronic pen system, it is possible to perform a predetermined operation such as drawing by holding an electronic pen with a hand, and to perform another operation by a finger of the other hand at the same time. It is also possible that while a user performs a predetermined operation by holding an electronic pen, another user who does not hold an electronic pen performs a predetermined operation by his/her finger. The usability can, therefore, be improved by using an electronic pen and a finger separately.
In connection with this demand, a technology is known in which a directing subject that performed a touch operation is identified as either an electronic pen or a finger based on the contact area. Specifically, the directing subject is identified as a finger when the contact area is large, and it is identified as an electronic pen when the contact area is small. (see Related Art 2).                Related Art 1: Japanese Patent Application Publication No. 2008-118301        Related Art 2: Japanese Patent No. 2599019        Related Art 3: Japanese Patent Application Publication No. H06-19849        Related Art 4: Japanese Patent No. 2877089        Related Art 5: Japanese Patent Application Publication No. 2000-172421        